This invention relates generally to a novel flood control apparatus for sensing a flood and for discontinuing the flow of fluid to an appliance or an entire household in response to a flood. More particularly, this invention concerns an automatic flood control valve adapted to shut off the flow of water to a water heater, washer or other appliance in the event of a flood resulting from the malfunctioning of such an appliance.
In the past, it has been common to employ a sensor capacitor in connection with a relaxation oscillator to actuate a solenoid shutoff valve. Such prior art arrangements require relatively complicated adjustments of the sensitivity of the oscillator in order to provide appropriate sensitivity without false alarms. Such arrangements depend upon the leakage resistance of the capacitor to change the operating state of the relaxation oscillator.
The operation of such prior art devices is affected by water condensation that may occur in the environments encountered in many appliance installations. Such condensation may affect the leakage resistance of the sensor capacitor. Moreover, the construction of the sensor capacitor may be critical; and suitable sensor capacitors are not readily available. Many prior art sensor capacitors require wick arrangements to induce wetting of the sensor.
Prior art relaxation oscillator devices are expensive to operate because they require electrical current during normal operation. The valve is held in an open position by energizing a solenoid valve coil. Thus, the energy requirements for such prior art devices renders them unsatisfactory and impractical. An example of such a device is disclosed in U.S. Pat. No. 3,770,002, dated Nov. 6, 1973, issued to Lawrence C. Brown.
Other prior art devices have employed open topped water collecting trays placed beneath an appliance. An example of such a prior art device is disclosed in U.S. Pat. No. 3,473,553, to Thomas H. Collins, issued Oct. 21, 1969.
Collins utilizes a float-actuated electrical switch to close an electrical circuit when sufficient water collects in the tray. A plunger is depressed to open a normally closed valve; and a latch pin is used to hold the valve in the open position. The pin is retracted by means of a solenoid, thus permitting the valve to be closed by a spring.
Such devices are unsatisfactory because a significant amount of water must leak from the appliance before the float will activate the switch. Moreover, such devices have the disadvantage of utilizing movable parts for the water detection apparatus. It will be appreciated that such float mechanisms may become rusted or may stick, and consequently not move in response to water in the collecting tray. If the float does not move, then the device will not operate to shut off the flow of water.
A further disadvantage of the Collins device is the relatively slow reaction time of the device. The device will not operate to close the value until enough water has filled the collecting tray to move the float. A small leak may take a relativey long time to fill the collecting tray.
It will be appreciated that the Collins device is ineffective when the leak is so situated that water does not fall into the tray. Moreover, the valve must be placed immediately adjacent to the appliance in the Collins device.
Other prior art devices, such as the device disclosed in U.S. Pat. No. 3,874,403, dated Apr. 1, 1975, issued to Wayne L. Fischer, have employed fluid sensitive switches to directly switch solenoids. Such prior art devices are unsatisfactory because a significant amount of current must pass through the fluid in order to actuate the solenoid. Special sensitive solenoids may be required to close conventional control valves, because the amount of current that may be passed directly through the water or fluid in series with the solenoids may be limited. The imperfect conductivity of water often presents a significant resistance in series with the solenoids. A significant voltage drop may occur across the water.
A device for controlling lawn sprinklers is disclosed in U.S. Pat. No. 3,823,874, to Herbert Kroeck, issued July 16, 1974. The Kroeck device draws a significant amount of current during normal operation to energize a solenoid in order to hold a normally closed control valve open. Kroeck discloses a trough adapted to collect water from the sprinkler and to shut off the valve when the water reaches a predetermined level. The Kroeck device requires two transistors for its operation.
Another prior art device for controlling lawn sprinkling systems is disclosed in U.S. Pat. No. 3,500,844, issued Mar. 17, 1970, to George E. Sanner. This device has a rain switch with a fast reaction time. The Sanner device is adapted to shut off the flow of water to a sprinkler system when the rain switch becomes wet from rain water. Only a small amount of moisture collects on the rain switch base. The large area of the rain switch is adapted to facilitate the rapid evaporation of water from the rain switch. The Sanner device is designed to resume the flow of water to the sprinkler system substantially coterminously with the cessation of rain. Thus, the Sanner device would be impractical for use as a flood control apparatus. The timer in the Sanner device is also not adapted for flood control applications.
The above prior art devices are unsatisfactory in that they require the continued presence of water in order to maintain the valve in the shutoff position. If a flood occurred and the device operated to shut off the valve, the valve would reopen when the water evaporated and thus once again permit fluid to flow into a damaged or leaking appliance. If a home owner were away on a trip or vacation, a damaged appliance might not be detected for an extended period of time. Thus, the prior art devices could allow the area of the appliance to be repeatedly flooded over a period of several days until someone returned and discovered the damaged appliance. Moreover, the energy requirements of prior art devices which require electrical current to maintain a valve in an open position during normal operation can represent a significant expense in the operation of such devices.
A probe-type liquid detector is disclosed in U.S. Pat. No. 4,126,857, issued to Frederick N. Lancie, dated Nov. 21, 1978. The Lancia device is adapted to set off an audible alarm upon detection of water. However, the Lancia device is unsatisfactory because it requires human intervention to prevent flooding from the damaged appliance. If no one is present in the nearby vicinity when the flood occurs, the Lancia device would be ineffective to prevent flooding and consequential damage to the area.
A "Flood Guard" device is offered for sale by Symtec, Inc., Farmington, Mich. This device produces an 1800 Hz buzzer sound when a flood condition is detected. The device is battery operated, and consequently requires that the batteries be replaced periodically. The batteries will also run down if the alarm sounds for more than a day. The "Flood Guard" is unsatisfactory because it is not fully automatic. It will not prevent flood damage without human intervention. It will be appreciated that significant damage can occur in the event of sudden flooding during the amount of reaction time that must normally elapse between the time that someone hears the alarm and the time that it takes someone to stop the flow of water. It will also be appreciated that significant damage can occur in the event that no one is present when the alarm sounds.
Other representative prior art patents are U.S. Pat. Nos. 3,200,388; 3,069,671; 2,043,857; and 1,786,843.
Many of the above prior art devices are unsatisfactory because they are not easily installed upon existing appliances; they have also been expensive and difficult to operate. Many prior art devices are bulky and difficult to install. Some prior art devices are not fully automatic and will not prevent flood damage.
While such prior art arrangements have exhibited a degree of utility in preventing damage due to flooding caused by a damaged or leaking appliance, room for significant improvement remains. The problems enumerated in the foregoing are not intended to be exhaustive, but rather are among many which tend to impair the effectiveness of previously known flood control devices. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that prior flood control valves appearing in the art have not been altogether satisfactory.